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Mass Wasting
The downslope movement of rock and soil due to
gravity
From A Homeowners Policy(Why this is so important)
From A Homeowners Policy(Why this is so important)
What triggers mass wasting?
1. Gravity
2. Water Diminishes particle
cohesion Water adds weight
3. Oversteepening of slopes
Stable slope angle (angle of repose) is different for various materials
4. Removal of anchoring vegetation, such as by fire
5. Ground vibrations from earthquakes
May cause expensive property damage
Can cause liquefaction – water saturated surface materials behave as fluid-like masses that flow
Landslide triggered by 1994 North earthquake in S. California
Forms of mass wasting
1. Slump Movement along a
curved surface
2. Rockfall Blocks of
bedrock slide down a slope
Generally very fast and destructive
Rockfall Debris
Rockfall in action
3. Mudflow Consists of soil with
a large amount of water
Dry areas after heavy rain
A lahar from the 1980 Mt. St. Helens eruption
Box 09.01.f2a
Box 09.01.f2b
4. Landslide Rock and soil
suddenly fall Steep slopes
Landslide photo
5. Creep Very slow
movement downhill
Creeping Headstones
6. Solifluction Slow, downslope flow of water
saturated soil over frozen layers
Curved trees Stuck windows Stuck doors Leaning walls Plaster cracks Foundation cracks Damaged chimneys Leaning poles Scarps Toes Seeps Pavement damage
Curved trees Stuck windows Stuck doors Leaning walls Plaster cracks Foundation cracks Damaged chimneys Leaning poles Scarps Toes Seeps Pavement damage
Recognizing Problem AreasRecognizing Problem Areas
Be suspicious! Check target and adjacent properties Some problems can be fixed Fixes are temporary and expensive Get expert advice Soil Conservation Service /
Geological Survey
Be suspicious! Check target and adjacent properties Some problems can be fixed Fixes are temporary and expensive Get expert advice Soil Conservation Service /
Geological Survey
Before buying on a hillside:Before buying on a hillside:
Get expert advice Your efforts will probably give temporary relief
Support the base Anchor through slip plane Lower water table Runoff control Plant vegetation Excavate slide mass
Get expert advice Your efforts will probably give temporary relief
Support the base Anchor through slip plane Lower water table Runoff control Plant vegetation Excavate slide mass
Landslide StabilizationLandslide Stabilization
Landslide Diagnosis "A"Landslide Diagnosis "A"
Landslide Diagnosis "B"Landslide Diagnosis "B"
Landslide Diagnosis "C"Landslide Diagnosis "C"
Landslide Diagnosis "D"Landslide Diagnosis "D"
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